Over 50,000 people in Germany are diagnosed with pulmonary cancer each year, with most of them developing tumor-based stenoses of the airways. In case of inoperable tumors, a palliative treatment is performed to increase patients’ life quality and decrease the overall number of hospitalizations.
During the treatment, a stent is implanted to keep the airways open. To date, most of these stents are tubes consisting of either metal meshes or silicon. A serious disadvantage of silicon stents is the coverage of the airway’s mucosa inhibiting the natural mucus transport and causing an increased mucus accumulation on the proximal end of the stent. This leads to impaired respiration and furthers the risk of restenosis. In contrast, metal mesh stents allow for reepithelialization. However, the metal mesh’s open pores carry the risk of tumor ingrowth and therefore possible restenosis of the airway.
A biologic pulmonary stent was developed during the project „PulmoStent – Development & Evaluation of a Viable Stent Device for the Treatment of Broncho Tracheal Cancer“ under the project management by the NRW Schwerpunktprofessur Biohybrid & Medical Textiles (BioTex) as part of the Seventh EU Framework Programme.
The PulmoStent is a multi-layer structure with a braided nitinol stent as backbone, a mechanical separating layer in form of a polyurethane nonwoven, and an artificial living mucosa on the inner side (see Figure 1). Optionally, therapeutics can be incorporated in the nonwoven. Not least on account of the innovative nonwoven cover, PulmoStent combines the advantages of commercially available airway stents while simultaneously eliminating their disadvantages. The permeable polyurethane nonwoven provides the stent inside with nutrients, enabling its epithelialization and therefore ensuring the mucus transport. In addition, the nonwoven prevents rapid tumor ingrowth into the stent in order to obviate pulmonary restenosis. Specific tumor drugs further locally inhibit tumor growth. The special geometry prevents stent migration due to physiological stresses caused for example by coughing.
The optimization of the PulmoStent design and the subsequent validation of the PulmoStent concept constitute the objectives of this project.
Amongst CVE competences provided for the joint project is the manufacturing of multi-functional nonwovens by means of a custom-developed spraying machine. As one of the essential project partners, CVE contributes its technical expertise by further enhancing the polyurethane nonwoven. Thus, nonwovens are manufactured at CVE using the spray atomization facilities. By variation of process parameters, the nonwoven structure is modified in order to enhance adhesion and proliferation of respiratory epithelial cells.
A pre-clinical evaluation is part of the validation. It contains an assessment of the PulmoStent’s biological safety and the establishment of a manufacturing process in line with GMP standards. In addition, the stent’s overall performance is verified via direct in vivo comparison with another commercially available pulmonary stent.
This project is sponsored by the Federal Ministry of Education and Research, support code 03VP03290.
NRW-Schwerpunktprofessur Biohybrid & Medical Textiles (BioTex), Institute of Applied Medical Engineering, Universitätsklinikum RWTH Aachen University and Institut für Textiltechnik of RWTH Aachen University
Clinic for Cardiology, Pneumology, Angiology and Internal Intensive Medicine (Medical Clinic I) of Universitätsklinikums RWTH Aachen University